Doping of organic semiconductors is crucial for the operation of organic (opto)electronic and electrochemical devices. Typically, this is achieved by adding heterogeneous dopant molecules to the polymer bulk, often resulting in poor stability and performance due to dopant sublimation or aggregation. In small-molecule donor–acceptor systems, charge transfer can yield high and stable electrical conductivities, an approach not yet explored in all-conjugated polymer systems. Here, we report ground-state electron transfer in all-polymer donor–acceptor heterojunctions. Combining low-ionization-energy polymers with high-electron-affinity counterparts yields conducting interfaces with resistivity values five to six orders of magnitude lower than the separate single-layer polymers. The large decrease in resistivity originates from two parallel quasi-two-dimensional electron and hole distributions reaching a concentration of ∼10¹³ cm^–2. Furthermore, we transfer the concept to three-dimensional bulk heterojunctions, displaying exceptional thermal stability due to the absence of molecular dopants. Our findings hold promise for electro-active composites of potential use in, for example, thermoelectrics and wearable electronics.

有机半导体的掺杂对于有机（光电）电子和电化学设备的运行至关重要。通常，这是通过将异质掺杂剂分子添加到聚合物本体中来实现的，由于掺杂剂的升华或聚集，常常导致较差的稳定性和性能。在小分子供体-受体系统中，电荷转移可以产生高而稳定的电导率，这是全共轭聚合物系统中尚未探索的方法。在这里，我们报告了全聚合物供体-受体异质结中的基态电子转移。将低电离能聚合物与高电子亲和性对应物结合在一起，可以得到导电界面，其电阻率值比单独的单层聚合物低五到六个数量级。〜 10 ¹³ 厘米^-2。此外，我们将概念转换为三维体异质结，由于不存在分子掺杂剂，因此显示出出色的热稳定性。我们的发现为电活性复合材料在热电和可穿戴电子产品中的潜在应用提供了希望。